JP2936380B2 - Lens drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for a photographic lens in a camera or the like.

[0002]

2. Description of the Related Art Conventionally, a driving device such as a photographing lens in a camera or the like drives a lens for adjusting a focal point and switching a focal length by a configuration of a helicoid screw and a feed screw. Therefore, high-precision control is required to affect the resolution of the camera, and it is necessary to increase the precision and tolerance of mechanical parts in order to perform desired lens driving. Therefore, when these mechanical parts are manufactured by plastic molding or the like, there has been a problem that maintenance of the mold a plurality of times is necessary to maintain accuracy.

[0003]

Therefore, in the present invention, it is necessary to perform a desired lens drive by correcting a lens drive amount with respect to an error of each mechanical part, and to increase the precision of the mechanical part. Therefore, the purpose is to facilitate the maintenance of the mold.

[0004]

To achieve the above object, according to an aspect of, the lens driving device of the present invention includes a lens barrel movable in an optical axis direction, and a drive means for driving the lens barrel, Les
Exceeding the design value, which is the design drive amount of the lens barrel
And a correction means for providing a specified range having a certain width on the shortage side and correcting the drive amount of the lens barrel within the specified range, and control means for controlling the driving means,
The driving amount of the lens barrel reaches the lower limit of the specified range.
The drive amount is within the specified range by the correction means.
It is to be corrected to the upper limit . Also preferably, before
The specified range is based on the design value and is the maximum of the lens barrel.
The value of 1/2 of the small drive amount is provided on the excess side and the shortage side . More preferably, in the focus adjustment at the time of manufacturing, a predetermined
Of the focus adjustment distance and the driving amount of the lens barrel
Set to match the design value .

Also, a lens barrel movable in the optical axis direction, driving means for driving the lens barrel, correction means for correcting the amount of drive of the lens barrel, and control for controlling the driving means When the driving amount of the lens barrel exceeds 1/2 of the minimum driving amount, the driving unit is controlled by a correction value output from the correcting unit.

Further, a lens barrel movable in the optical axis direction, a driving means for driving the lens barrel, a correcting means for correcting a driving amount of the lens barrel, and a control for controlling the driving means Means for controlling the driving means in accordance with a correction value output from the correction means when the drive amount of the lens barrel exceeds a prescribed value with respect to a distance for performing focus adjustment of the photographing lens.

[0007]

The correction value of the lens drive amount is stored in the correction means in accordance with the error of the mechanical parts constituting the lens drive device, and the lens drive amount corresponding to the predetermined calculation result is calculated at the point where the correction is performed. The lens drive is performed by adding a correction based on the correction value.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the preferred embodiments shown in the accompanying drawings. In FIG. 1, a photometric circuit 2
Reference numeral 1 denotes a known light receiving element for measuring the luminance of a subject, and outputs a luminance information signal of the subject. The distance measuring circuit 22 is a part of a device for measuring a distance to a subject,
Outputs the measured distance signal. The control circuit 23 outputs an operation signal to the shutter motor drive circuit 25 based on the luminance information signal from the photometry circuit 21, and outputs an operation signal to the LD motor drive circuit 26 based on the distance information signal from the distance measurement circuit 22. Is output. In this case, the control circuit 23 controls the LD motor drive circuit 26 based on data of a correction circuit 24 described later.

The shutter 27 includes a shutter motor 8 and a lens motor 12 as described in detail in FIGS. 2 to 4, and is controlled by a shutter motor drive circuit 25 and an LD motor drive circuit 26, respectively.

FIG. 2 shows an initial state before the operation of the shutter 27. The shutter base plate 1 has a fixed barrel portion 1a for supporting the lens barrel 2. A female helicoid 1b is cut in the inner periphery of the fixed lens barrel 1a, and a male helicoid 2a formed in the lens barrel 2 is screwed. Therefore, the lens barrel 2 moves in the optical axis direction with the rotation described later, and moves the photographing lens to the in-focus position, or the focal length changes.

A lens setting ring 3 is rotatably fitted on the outer periphery of the fixed lens barrel 1a for rotating the lens barrel 2. The lens setting ring 3 has a protrusion 3
a. The projecting portion 3a is engaged with an engaging portion 2b of the lens barrel 2, and the lens barrel 2 is
And rotate together. This lens setting ring 3
Is urged to rotate clockwise by a spring 4.

The lens setting ring 3 has a gear 3b on the outer periphery and is connected to the gear 6a of the ratchet 6 via the intermediate wheel 5. Ratchet 6 is shutter base plate 1
It rotates around the upper axis 1c. A plurality of claws 6b are formed on the outer periphery of the ratchet 6 at an equal pitch. Uncle 7
Swings about a shaft 1d on the shutter base plate 1 to form a pair of locking claws 7a and 7b, which are configured to alternately mesh with ratchet claws 6b. In addition, locking claws 7a,
The engagement position between the ratchet 7b and the pawl 6b of the ratchet 6 is shifted in phase by half the pitch of the pawl 6b. That is, when the pallet fork 7 rotates from the state in which the locking claw 7a and the claw 6b of the ratchet 6 are engaged to the state in which the locking claw 7b and the claw 6b are engaged, the ratchet 6 moves the intermediate wheel 5 during that time. The bias of the spring 4 causes the claw 6b to rotate by half the pitch. In order to swing the pallet 7, the pallet 7 is connected to a oscillating motor 8 that can rotate forward and backward.

The ratchet 6 is formed by laminating a gear 6a, a claw 6b, and a locked portion 6c. In the position shown in FIG. 2 showing the initial state of the lens, the ratchet 6 is locked by the locking portion 9a of the locking lever 9 engaging the locked portion 6c. The locking lever 9 is urged by a spring 10 in a direction in which the end 9 a is engaged with the locked portion 6 c of the ratchet 6. When the driving ring 11 rotates clockwise, the other end 9b of the locking lever 9 is pushed by the cam portion 11a of the driving ring 11 to rotate around the shaft 9c, and the end 9a and the locking portion 6c are rotated.
Is released. Drive ring 1
Numeral 1 is rotatably fitted to the outer periphery of the fixed lens barrel 1a of the shutter base plate 1. The drive ring 11 has a gear portion 11b and meshes with a gear 12a of the drive motor 12,
It is rotatable in the forward and reverse directions. The pin 11 c of the drive ring 11 is configured to engage with the engaging portion 3 c of the lens setting ring 3 and rotate the lens setting ring 3 counterclockwise against the bias of the spring 4.

FIG. 3 shows a sector opening / closing section arranged on the back side of the shutter base plate 1 in FIG.
Is rotatably fitted to the outer periphery of the fixed lens barrel 1a of the shutter base plate 1, and is urged counterclockwise by a spring 14. The long groove 15a of the sector 15 is fitted to the pin 13a of the sector ring 13, and the sector 15 rotates around a fixed shaft 1e provided on the shutter base plate 1 with the rotation of the sector ring 13. Engagement part 13 of sector ring 13
b is engageable with the pin 11d of the drive ring 11,
When the drive ring 11 rotates clockwise, the sector ring 1
3 is also configured to rotate against the spring 14.

Next, correction of lens driving will be described with reference to FIGS. The mechanical components that determine the lens drive amount include the swing motor 8 that supplies the driving force and the transmission mechanism that transmits the output to the lens barrel 2 as described above.
If, although Ru lens barrel 2 der, machine parts accuracy of these transfer mechanisms, the backlash and the fitting backlash by error occurs,
The lens drive amount becomes insufficient with respect to the design reference value, and further, the lens drive amount becomes insufficient according to the distance.
However, since the mechanical parts of these transmission mechanisms are manufactured by molds, the shortage of the lens drive amount does not cause variations due to the individual shutters, and the shortage is stable and almost the same. Therefore, based on the distance that performs focus adjustment of the taking lens in several shutter Me pre, the driving amount of the lens barrel at each distance measured versus the design standard value
The driving amount of the lens barrel within the specified range ΔD is set to の of the minimum driving amount ΔP on the excess side and the shortage side of the driving amount.
Then, it is determined whether or not the value exceeds the specified range ΔD, and correction is performed at a point where the lower limit of the specified range is reached . To perform the correction, the correction circuit 24 is a non-volatile readable and writable memory (electrically erasable programmable read only memory, hereinafter referred to as an EEPROM), and is defined at a point where the lower limit of the specified range is reached.
A correction value for driving the lens barrel 2 up to the upper limit of the fixed range ΔD is stored in the EEPROM, and the control circuit 23 performs control corresponding to the calculation result calculated from the outputs of the photometry circuit 21 and the distance measurement circuit 22. , The correction circuit 24
A desired lens drive is performed by correcting the lens drive amount in the drive direction by the correction value output from. In Figure 6, two
Correction is applied at some points, and at other points
Is not corrected, the driving of the lens barrel 2 is indicated by a broken line in FIG.
Make a movement like this.

In this embodiment, the configuration of driving the lens has been described with the configuration of the helicoid screw, but it may be configured with the feed screw. In this embodiment, the correction of the drive amount shortage has been described, but the correction of the drive amount excess may be performed. Furthermore, in the present embodiment, the reference for alignment is set at the lens focus adjustment point, but the reference may be set at any distance.

[0017]

By correcting the lens drive amount corresponding to the error of the mechanical parts according to the present invention, Ru proper lens driving is obtained. Ma
And it does not require high precision mechanical parts, Ru can facilitate the type of Men tenant <br/> scan.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a component configuration of a lens driving unit according to the embodiment of the present invention.

FIG. 3 is a diagram showing a component configuration of a sector opening / closing unit according to the embodiment of the present invention.

FIG. 4 is a sectional view showing a component configuration according to the embodiment of the present invention.

FIG. 5 is a diagram illustrating a lens drive amount before correction according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating a corrected lens drive amount according to the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 shutter base plate 2 lens barrel 3 lens setting ring 6 ratchet 7 ankle 8 swing motor 9 locking lever 12 drive motor 21 photometry circuit 22 distance measurement circuit 23 control circuit 24 correction circuit 25 shutter motor drive circuit 26 LD motor drive circuit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-306609 (JP, A) JP-A-4-55806 (JP, A) JP-A-4-285905 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G02B 7/02-7/105 G02B 7/012-7/16 G03B 3/10-3/12 G03B 13/34-13/36

Claims (3)

(57) [Claims] A lens barrel movable in an optical axis direction; a driving unit for driving the lens barrel;
Excess and insufficiency with respect to the design value, which is the design drive amount
Correction means for providing a specified range having a certain width on the side and correcting the drive amount of the lens barrel within the specified range ,
Control means for controlling the driving means, wherein the lens
When the driving amount of the lens barrel has reached the lower limit of the specified range,
The driving amount is supplemented to the upper limit of the specified range by the correction means.
Lens driving apparatus characterized by positive to. 2. The method according to claim 1, wherein the specified range is
1/2 of the minimum driving amount of the lens barrel based on a design value
Lens driving device characterized in that the value of (1) is provided on the excess side and the shortage side . 3. The manufacturing method according to claim 1, wherein
In the focus adjustment, a predetermined focus adjustment distance
So that the design value of the drive amount of the lens barrel coincides with the design value.
A lens driving device characterized by being set .